[yocto] Conditional Configuration Fragments

[Paul Eggleton]

On Tuesday 10 June 2014 12:04:19 Bruce Ashfield wrote:
> On 14-06-10 11:11 AM, Pierre Yves MORDRET wrote:
> > On Monday 09 June 2014 09:56:20 Paul Eggleton 
<paul.eggleton at linux.intel.com> wrote:
> >> On Monday 09 June 2014 12:41:36 Bruce Ashfield wrote:
> >>> On 14-06-09 11:26 AM, Pierre Yves MORDRET wrote:
> >>>> Hello,
> >>>> 
> >>>> I really don't know whether this is feasible or not, but I'm trying to
> >>>> build a yocto image (custom image) with conditional configuration
> >>>> fragments.
> >>>> 
> >>>> Today I have 2 image type: one for deployment purpose and another for
> >>>> debug purpose. Debug images is only a superset of deployment image with
> >>>> additional debug capabilities: nothing else.
> >>>> 
> >>>> However now I would like to add additional linux kernel features to
> >>>> this
> >>>> debug image (ex: CONFIG_DEBUG_INFO=y).
> >>>> 
> >>>> I want to add this feature into debug image, but NOT in deployment
> >>>> image.
> >>>> 
> >>>> I was thinking to create a .bbappend to my linux .bb file, but again I
> >>>> don't see how to use .bbappend in a conditional way (based on image
> >>>> name
> >>>> for instance)
> >>>> 
> >>>> Do you have any idea to perform such request ?
> >>> 
> >>> Fragments are either just added to the SRC_URI or KERNEL_FEATURES via
> >>> the normal variable assignment rules.
> >>> 
> >>> So if you have something that you can test on (image/distro feature as
> >>> an example), you can use anonymous python and do a conditional
> >>> assignment.
> >>> 
> >>> Others on the list may have more elegant suggestions!
> >> 
> >> This can't work for what Pierre is asking for. You can't have a single
> >> recipe built differently depending on what image is being built - our
> >> system does not work that way. At a basic level, recipes create
> >> packages, and then the image recipe selects which packages should go
> >> into the image.
> >> 
> >> Given that the kernel does not produce named packages in our system, I'm
> >> not sure we currently have a way to build two different kernel recipes
> >> and select one in one image and another in another image (which is the
> >> way we normally handle this kind of requirement with other recipes.)
> >> Probably the only way to do this is to have two completely separate
> >> build directories.
> > 
> > Many Thanks for your answers.
> > Thus I was thinking of making 2 separate linux.bb, one for deployment and
> > the other for debug (i.e. linux-debug.bb) and update
> > PREFERRED_PROVIDER_virtual/kernel accordingly. But is there an automatic
> > way to select proper .bb (linux.bb or linux-debug.bb) file like setting
> > this variable(PREFERRED_PROVIDER_virtual/kernel) within the .bb image
> > file ? Won't it work ?
> > 
> > Another option which is coming on top of my mind:
> > SRC_URI_append_<image-name> = " file://configuration_segment.cfg"
> > Is it something realistic and working ?
> 
> The image name would have to be an OVERRIDE value for variables.
> Last I checked it wasn't, but perhaps Paul can straighten out that
> point as well :)

No, you can't do this, nor can you select PREFERRED_PROVIDER from the image. 
You cannot influence the building of other recipes from the image recipe at 
all.

As I said before, the only way to make this work would be if the kernel 
produced uniquely named packages that could be selected from the image; our 
kernel recipes don't currently do that though, and it would be a fairly major 
change in order to do that.

Cheers,
Paul

-- 

Paul Eggleton
Intel Open Source Technology Centre